The present invention relates to a fluid pressure sensing apparatus for sensing the pressure in a fluid passageway. The sensing apparatus is particularly useful for measuring and monitoring the pressure in a high pressure fuel injection line for an internal combustion engine.
It is desirable to measure and monitor the fuel injection pressure in an engine fuel injection system during design of the system, operation of a vehicle powered by the engine and maintenance of the system. Such measurement has heretofore been made using a Bourdon tube. However, this type of pressure gage provides an unstable indication and is extremely sensitive to temperature variations which change the reading. Although it is possible to convert the output of a Bourdon tube into an electrical signal, the electrical components required for such conversion are also sensitive to temperature variations. Such a system is also susceptible to erroneous pressure reading by marginally trained personnel.